Childhood malnutrition is a public health problem of global proportions. Stunted children have numerous developmental difficulties, including deficits in cognitive functioning and poor school performance. Research with animals has demonstrated a link between early malnutrition and heightened emotional reactivity, leading to the hypothesis that stress could interfere with cognitive functioning. However, there has been almost no research with humans exploring this possibility. In my proposed doctoral research, I will investigate the role of impaired stress response as a potential mediating variable contributing to negative developmental outcomes in malnourished children. I will test the hypothesis that children who have suffered a history of malnutrition are less able to adapt to novel environments, and become frustrated and anxious more easily than adequately nourished children. To address this important question, stunted and non-stunted Jamaican children will be presented with psychological stressors (e.g. interview, mental arithmetic, frustrating tasks) and physical stressors (e.g. isometric handgrip). The stress response of the malnourished and adequately nourished children will be compared using behavioral measures in combination with physiological measures of the cardiovascular, adrenocortical, and autonomic nervous systems. The findings of this research will increase our understanding of how heightened susceptibility to stress may contribute to the poor cognitive and social development of malnourished children.